There exists a wide variety of compressors or pumps which utilize electrodynamic resonating motors. Usually what is involved is that a motor provides a driving force to a piston which provides the compression action on a working liquid or gas involved.
In this regard, such motors normally have a permanent magnet armature with a coil wound about a support and positioned within the field provided by the magnet. A compression piston is usually coupled to the armature and the armature held in a rest position by way of one or more main or resonance springs. When the coil is energized, a magnetic force is generated to drive the piston. The resonance spring causes the piston to oscillate back and forth to provide compression of the gas or liquid. Arrangements which operate in a manner such as this, or similar thereto, can be found in U.S. Pat. Nos. 3,814,550 issued June 4, 1974, 3,781,140 issued Dec. 25, 1973 and 3,325,085 issued June 13, 1967. These devices typically utilized circular type plungers which had certain disadvantages for which corrective measures were necessary.
Motors having flat type plungers are available. Such flat type plungers, while having certain advantages, particularly the reduction of weight, etc., have other disadvantages such as misalignment, undesired rotation, uncompensated temperature differential expansion, etc. Moreover, typical flat plunger designs are somewhat complicated and expensive.
There is known a linear electrodynamic motor having a flat plunger arrangement therein which involves the use of an electrodynamic linear motor for use in a variety of devices. The motor therein comprises a stack of flat magnetic members separated by insulated spacer members and held together by tie rods. The magnetic members are shaped as elongated flat laminated plates having at each end an enlarged opening to receive hollow guide rods thereby making up a basic plunger core assembly. A centered connecting rod is provided and coupled to a compression piston at one end. A centering or resonance spring may be provided at the opposite end, however due to the centering effect of the stator resulting from the magnetic driving force depending upon the application involved, the centering spring may be eliminated. The hollow guide rods are slideably mounted on respective bearing rods oppositely positioned and maintained by supporting arms. To a certain extent these arms are provided with an amount of flexure to allow for temperature expansion and contraction of the plunger assembly. The plunger core assembly is restricted to a reciprocal path guided by the guide or bearing rods, thereby advantageously maintaining the proper alignment of the plunger core during operation.
Positioned about and spaced from the plunger core is a stator assembly which is mounted to the housing. The application of current thereon causes a driving force on the plunger core which in turn drives the piston for compression of the working liquid. The piston is ported to regulate this stroke with the stator assembly and/or spring arrangement causing the plunger to oscillate in reciprocating motion.
The flat plunger configuration eliminates the flux return path which greatly reduces the plunger mass. The flat plunger is prevented from rotating due to the guide rods. Thus, by that arrangement an efficient motor is provided, which allows for a rugged compact design which is both efficient and durable, yet relatively inexpensive.
It has been found that many of the features in that arrangement are desirable in an arrangement involving a linear air compressor. It is therefor desirable to include such features and others in a linear air compressor, especially one of a relatively small size that has expanded output capacity, and which is efficient yet economic and durable.